Preparation of bis-(2-carboxyalkyl) sulfones



Patented Oct. 18, 1949 UNITED STATES PATENT OFFICE PREPARATION OF BIS-(Z-CARBOXYALKYL) SULFONES Marvin R. Frederick, Wadsworth, Ohio, assignor to The B. F. Goodrich Company, New York, N. Y., a corporation of New York No Drawing. Application September 25,1948,

Serial No. 51,310

8 Claims. (Cl. 260537) heretofore been obtained only with difliculty and/or from relatively costly raw materials.

Since ionizable inorganic salts such as hyposulfites do not ordinarily react with organic compounds in which the atoms are bound together by the sharing of electrons (beta-lactones being representative of this type of organic compound), this reaction is unique in chemical synthesis. Its

I mechanism has not been established with certainty, but it is believed that the reaction proceeds (as illustrated in the case of sodium hyposulfite and beta-propiolactone) as follows, the

lactone ring cleaving between the ring oxygen and the beta carbon atom:

CHr-CHrC-ONQ! is economically obtained from ketene and formaldehyde.

It is further disclosed in a copending application, Serial No. 620,655, filed October 5, 1945, now Patent #2,449,987, that beta-propiolactone and other beta-lactones will react with ionizable inorganic salts in the presence of a polar solvent to give useful beta-substituted carboxylic acids. For example, common salt, sodium chloride, reacts with beta-propiolactone in aqueous solution to give, on acidification of the solution, betachloropropionic acid.

I have now discovered that beta-propiolactone and other saturated aliphatic beta-lactones will react with Water-soluble hyposulfites in the presence of a polar solvent to yield a soluble complex (believed to be a salt of an acid of the formula wherein each R is a member of the class consisting of hydrogen and alkyl) which upon acidification and heating gives ofi sulfurdioxide, there being obtained as a final product of the reaction a bis-(2-carboxyalkyl) sulfone. This reaction provides a convenient and economical method for preparing useful sulfones, many of which have Hr-CHl-C-ONB action in aqueous solution utilizing a water-soluble beta-lactone is by far the most convenient method of procedure, although with certain reactants the use of polar organic solvents such as alcohols, organic acids, nitro-parafins, or the like may be desirable. Other conditions such as concentration of reactants and temperature of reaction are not critical factors and may be Varied widely. While preferred conditions for specific reactions will be set forth in the examples hereinbelow, it may be said in general that the use of from 2 to 5 molecular proportions of betalactone to 1 molecular proportion of the hyposulfite (a ratio of 2 moles of the beta-lactone to 1 mole of the hyposulfite being stoichiometricallv required for the reaction) and the use of temperatures of from 10 C. to 50 C. are most desirable.

Water dissolves hyposulfites and many beta-lactones; hence the carrying out of the re- One preferred method of carrying out the reaction consists in placing a water solution of the hyposulfite (preferably a freshly prepared solution since hyposulfite solutions tend to be some- What unstable) in a reaction Vessel fitted with a reflux condenser, stirrer and suitable cooling means for controlling the temperature of the reaction. The beta-lactone is then added to the hyposulfite solution, which is maintained at the desired reaction temperature, at a rate of from 0.33 to 1 mole of lactone per hour after which the reaction mixture is acidified and heated, preferably to boiling, for approximately an hour. Upon cooling of the solution, the bis-(2-carboxyalkyl) -sulfone crystallizes and can be separated from unreacted materials and the polar solvent simply by filtering. The product may be obtained in a more pure form after recrystallization from glacial acetic acid or other solvent.

It is to be understood that the preferred procedure outlined above is not the only means of effecting the reaction of this invention, for any conventional reaction procedure, including reverse order addition of the reactants, may be adopted without seriously affecting the yield of the sulfone obtained. Also, it has been found that if the beta-lactone is diluted with about 1 mole of acetone per mole of the beta-lactone, higher yields of the sulfone are obtained, the addition of the beta-lactone to the hyposulfite solution is more easily controlled, and the slight tendency for the beta-lactone to react with itself is greatly decreased. Moreover, the product may be obtained by heating the acidified solution to temperatures below boiling, for example from 35 to 100 C., although a longer time (in the neighborhood of to hours) at the lowest temperature is required.

As disclosed hereinabove, any water-soluble hyposulfite may be utilized in the reaction of this invention. Because they are: water-soluble and exist in a relatively stable form, the hyposulfites of the elements of group I of the periodic table, especially sodium hyposulfite, potassium hyposulfite and lithium hyposulfite and hyposulfites of the elements of group II of the periodic table, especially calcium hyposulfite, magnesium hyposulfite, zinc hyposulfite and strontium hyposulfite are preferably employed in the reaction with beta-lactones, although other water-soluble hyposulfites such as iron hyposulfite may also be used so long as they are obtained in a suificiently stable form. In this connection it has been found that the hyposulfites may be stabilized somewhat by the addition of a small portion of the hydroxide having the same anion as the hyposulfite. Thus, for example, sodium hydroxide tends to increase the stability of sodium hyposulfite.

Beta-propiolactone, the simplest possible betapropiolactone, is preferably used in the reaction of this invention because of its lowcost and the ease with which it reacts with hyposulfites. However, the homologs of beta-propiolactone, that is, other saturated aliphatic beta-lactones such as beta-butyrolactone, beta-isobutyrolactone, betavalerolactone, beta-isovalerolactone, beta-ncaprolactone, alpha-ethyl beta propiolactone, alpha-isopropyl-beta-propiolactone, alpha-butylbeta-propiolactone, alpha-methyl-beta-butyrolactone, alpha-ethyl-beta-butyrolactone, betamethyl-betavalerolactone and the like may also be used advantageously.

The following specific examples, in which all parts are by weight, illustrate the reaction of hyposulfites with beta-lactones to obtain bis-(2- carboxyalkyl) sulfones. However, the examples Example I 193 parts (1 mole) of 90% sodium hyposulfite are mixed with 400 parts of water in a reaction vessel equipped with a stirrer, a reflux condenser and temperature measuring means. The solution is then cooled to a temperature of 25 C. and 144 parts (2 moles) of beta-propiolactone are slowly added over a period of two hours, after which most of the product is in solution with a minor part in suspension. The solution is next acidified with 292 parts of concentrated hydrochloric acid and boiled for 30 minutes. Upon cooling of the solution, the product crystallizes. The solid crystals are then removed from the solution by filtering and are washed with water. A 57% yield of substantially pure bis-(2-carboxyethyl) -sulfone (M. P. 215-21'l C.) is obtained after recrystallization from glacial acetic acid.

Example II Example I is repeated except that the betapropiolactone is diluted with 118.5 parts of acetone before the lactone is added to the hyposulfite solution and the temperature is maintained at from 1015 C. A 75% yield of bis-(2-carboxyethyl) -sulfone (M. P. 215-21'7 C.) is obtained.

Example III I Example I is repeated except that 800 parts of water are mixed with the sodium hyposulfite. Upon acidification and heating of the reaction mixture, a 32% yield of bis-(2-carboxyethyl) sulfone is obtained.

Example IV 228 parts (1 mole) of zinc hyposulfite are mixed with 500 parts of water in a reaction vessel placed in a cooling bath and fitted with a reflux condenser and stirrer. The solution is next cooled to-15 C. and 144 parts (2 moles) of beta-propiolactone are added slowly, the temperature of the reaction mixture being maintained between 15 C. and 35 C. during the addition of the lactone. The reaction mixture is then acidified with 300 parts of concentrated hydrochloric acid and heated to boiling for 60 minutes. Upon cooling, a crystalline product forms which is then removed from the reaction mixture by filtering and is identified as bis-(2-carboxyethyl) sulfone (M. P. 215-217 C.)

Example V Example IV is repeated except that 10 parts of solid sodium hydroxide are added to stabilize the hyposulfite solution. Bis-(2-carboxyethyl) sulfone is obtained in 63 yield.

When the above examples are repeated using other saturated aliphatic beta-lactones in place of beta-propiolactone, bis-(2-carboxyalkyl) sulfones are again obtained in substantial yield. For example, alpha-ethyl-beta-propiolactone reacts with an aqueous solution of a water-so1uble hyposulfite such as zinc hyposulfite to yield bis-(2- carboxybutyl) sulfone, and beta-butyrolactone reacts with potassium hyposulfite in solution in a polar solvent to give bis-(l-methyl-Z-carboxyethyl) sulfone. Similarly, bis-(2-carboxyalkyl) sulfones are also obtained when the reaction is carried out in other solvents such as alcohols, nitroparafiins and the like, and when other of the water-soluble hyposulfites mentioned above are' employed.

The bis-(Z-carboxyalkyl) sulfones obtained by the reaction of this invention are very useful compounds. For example, they are useful as stabilizers for polyvinyl chloride and the esters obtained by simple esterification of the sulfones are excellent plasticizers for use in preparing synthetic resin compositions, especially polyvinyl chloride compositions. The bis-(Z-carboxyalkyl) sulfones are also useful as chemical intermediates in the preparation of valuable organic compounds as well as for many other uses.

Although specific embodiments of the invention have been described hereinabove, it is not intended that it be limited solely thereto, but only to the spirit and scope of the appended claims.

I claim:

1. The method of preparing a bis-(2-carboxyalkyl) sulfone which comprises bringing together a saturated aliphatic beta-lactone with a solution of a water-soluble hyposulfite in a polar solvent, whereby to form a solution of a salt of an acid of the formula a saturated aliphatic beta-lactone with a solution of a water-soluble hyposulfite in a polar solvent, whereby to form a solution of a salt of an acid of the formula R R R\ /R (sioiho -5-03):

wherein R is a member of the class consisting of hydrogen and alkyl, at a temperature of from 10 C. to 35 C., acidifying the resulting solution, heating the resulting acidified solution, and recovering said bis-(Z-carboxyalkyl) sulfone.

3. The method of preparing bis-(2-carboxyethyl) sulfone which comprises bringing together beta-propiolactone and a solution of a watersoluble hyposulfite in a polar solvent, at a temperature of l0 C. to 35 C., acidifying the resulting solution, heating the resulting acidified solution to boiling, and recovering said bis- (2-carboxyethyl) sulfone.

4. The method of preparing bis-(2-canboxyethyl) sulfone which comprises bringing together beta-propiolactone and an aqueous solution of a water-soluble hyposulfite at a temperature of from 10 C. to 35 C., whereby to form an aqueous solution of a salt of the acid of the formula acidifying the resulting aqueous solution, heating the resulting acidified solution to boiling, and recovering said bis-(2-carboxyethy1) sulfone.

5. The method of preparing bis-(2-carboxyethyl) sulfone which comprises bringing together 2 moles of beta-propiolactone and an aqueous solution of 1 mole of an alkali metal hyposulfite at a temperature of 10 C. to 35 C., whereby to form an aqueous solution of an alkali metal salt of the acid of the formula acidifying the resulting aqueous solution, heating the resulting acidified solution to boiling, and recovering said bis-(2-carboxyethyl) sulfone.

6. The method of .preparing bis-(2-carboxyethyl) sulfone which comprises bringing together 2 moles of beta-propiolactone and an aqueous solution of 1 mole of sodium hyposulfite at a temperature of -10 C. to 35 C., whereby to form an aqueous solution of the sodium salt of the acid of the formula acidifying the resulting aqueous solution and heating the resulting acidified solution to boiling, and recovering said bis-(2-carboxyethyl) sulfone.

8. The method of preparing bis-(2-carboxyethyl) sulfone which comprises bringing together 2 moles of beta-propiolactone and an aqueous solution of 1 mole of zinc hyposulfite at a temperature of from l0 C. to 35 C., whereby to form an aqueous solution of the zinc salt of the acid of the formula acidifying the resulting solution with concentrated hydrochloric acid, heating the resulting acidified solution to boiling, and recovering said bis-(2-carboxyethyl sulfone.

MARVIN R. FREDERICK No references cited. 

